Drain the tofu block. Slice it into two flat slabs. Press them for 15 minutes by lining them with a kitchen towel and placing something heavy on them such as a pan. Or use a tofu press.
Preheat the oven to 400°F (200°C) and line a large sheet pan with a nonstick mat or parchment paper.
Slice the tofu slabs into 1-inch cubes and add them to a bowl that has a fitted lid or a gallon bag. Add a tablespoon of olive oil and the soy sauce. Close the bowl and shake it till the cubes are coated. Let this marinade absorb while preparing the other veggies.
Peel and cut the sweet potato into 1-inch cubes. Cut the red onion into chunks and separate some of the thicker layers. Add them to the sheet pan along with the kale in sections. Leave a quarter of the sheet pan empty for the tofu.
Mix the garlic powder and ginger with the cornstarch, then sprinkle it over the tofu. Close the bowl back up and shake it around gently until the cubes are fully coated. Place the tofu cubes on the sheet pan in a single layer.
Drizzle the vegetables with olive oil, and then sprinkle salt and pepper over everything, including the tofu.
Roast this for 30 minutes in the oven. Flip everything halfway through. Add more olive oil if anything looks like it's drying out and remove any veggies that look like they might burn.
Cook the quinoa while the other ingredients are roasting. You may need to rinse your quinoa if the package doesn't say “pre-rinsed.” Bring the quinoa and broth to a boil in a medium pot. Then, reduce the heat to a simmer. Cover the pot and cook the quinoa for 15 minutes. Fluff the quinoa with a fork once all of the broth is absorbed.
Make the optional spicy tahini sauce by whisking the sauce ingredients together. (The recipe is down below in the notes section.)
Divide everything across five bowls with the quinoa as the base. Top them with avocado slices, chia seeds, and sauce. Enjoy them now or save them for later.